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author | Linus Torvalds <torvalds@linux-foundation.org> | 2013-05-17 00:12:34 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-05-17 00:12:34 +0200 |
commit | d5fe85af85367d5892e4308f596de4e2a5fb9017 (patch) | |
tree | 8f31a641a0e24c3ecb38dc1396665149ac4b4746 /Documentation/power/states.txt | |
parent | Merge tag 'ntb-bugfixes-3.10' of git://github.com/jonmason/ntb (diff) | |
parent | Merge branch 'acpi-fixes' (diff) | |
download | linux-d5fe85af85367d5892e4308f596de4e2a5fb9017.tar.xz linux-d5fe85af85367d5892e4308f596de4e2a5fb9017.zip |
Merge tag 'pm+acpi-3.10-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management and ACPI fixes from Rafael Wysocki:
- intel_pstate driver fixes and cleanups from Dirk Brandewie and Wei
Yongjun.
- cpufreq fixes related to ARM big.LITTLE support and the cpufreq-cpu0
driver from Viresh Kumar.
- Assorted cpufreq fixes from Srivatsa S Bhat, Borislav Petkov, Wolfram
Sang, Alexander Shiyan, and Nishanth Menon.
- Assorted ACPI fixes from Catalin Marinas, Lan Tianyu, Alex Hung,
Jan-Simon Möller, and Rafael J Wysocki.
- Fix for a kfree() under spinlock in the PM core from Shuah Khan.
- PM documentation updates from Borislav Petkov and Zhang Rui.
* tag 'pm+acpi-3.10-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (30 commits)
cpufreq: Preserve sysfs files across suspend/resume
ACPI / scan: Fix memory leak on acpi_scan_init_hotplug() error path
PM / hibernate: Correct documentation
PM / Documentation: remove inaccurate suspend/hibernate transition lantency statement
PM: Documentation update for freeze state
cpufreq / intel_pstate: use vzalloc() instead of vmalloc()/memset(0)
cpufreq, ondemand: Remove leftover debug line
PM: Avoid calling kfree() under spinlock in dev_pm_put_subsys_data()
cpufreq / kirkwood: don't check resource with devm_ioremap_resource
cpufreq / intel_pstate: remove #ifdef MODULE compile fence
cpufreq / intel_pstate: Remove idle mode PID
cpufreq / intel_pstate: fix ffmpeg regression
cpufreq / intel_pstate: use lowest requested max performance
cpufreq / intel_pstate: remove idle time and duration from sample and calculations
cpufreq: Fix incorrect dependecies for ARM SA11xx drivers
cpufreq: ARM big LITTLE: Fix Kconfig entries
cpufreq: cpufreq-cpu0: Free parent node for error cases
cpufreq: cpufreq-cpu0: defer probe when regulator is not ready
cpufreq: Issue CPUFREQ_GOV_POLICY_EXIT notifier before dropping policy refcount
cpufreq: governors: Fix CPUFREQ_GOV_POLICY_{INIT|EXIT} notifiers
...
Diffstat (limited to 'Documentation/power/states.txt')
-rw-r--r-- | Documentation/power/states.txt | 30 |
1 files changed, 17 insertions, 13 deletions
diff --git a/Documentation/power/states.txt b/Documentation/power/states.txt index 4416b28630df..442d43df9b25 100644 --- a/Documentation/power/states.txt +++ b/Documentation/power/states.txt @@ -2,12 +2,26 @@ System Power Management States -The kernel supports three power management states generically, though -each is dependent on platform support code to implement the low-level -details for each state. This file describes each state, what they are +The kernel supports four power management states generically, though +one is generic and the other three are dependent on platform support +code to implement the low-level details for each state. +This file describes each state, what they are commonly called, what ACPI state they map to, and what string to write to /sys/power/state to enter that state +state: Freeze / Low-Power Idle +ACPI state: S0 +String: "freeze" + +This state is a generic, pure software, light-weight, low-power state. +It allows more energy to be saved relative to idle by freezing user +space and putting all I/O devices into low-power states (possibly +lower-power than available at run time), such that the processors can +spend more time in their idle states. +This state can be used for platforms without Standby/Suspend-to-RAM +support, or it can be used in addition to Suspend-to-RAM (memory sleep) +to provide reduced resume latency. + State: Standby / Power-On Suspend ACPI State: S1 @@ -22,9 +36,6 @@ We try to put devices in a low-power state equivalent to D1, which also offers low power savings, but low resume latency. Not all devices support D1, and those that don't are left on. -A transition from Standby to the On state should take about 1-2 -seconds. - State: Suspend-to-RAM ACPI State: S3 @@ -42,9 +53,6 @@ transition back to the On state. For at least ACPI, STR requires some minimal boot-strapping code to resume the system from STR. This may be true on other platforms. -A transition from Suspend-to-RAM to the On state should take about -3-5 seconds. - State: Suspend-to-disk ACPI State: S4 @@ -74,7 +82,3 @@ low-power state (like ACPI S4), or it may simply power down. Powering down offers greater savings, and allows this mechanism to work on any system. However, entering a real low-power state allows the user to trigger wake up events (e.g. pressing a key or opening a laptop lid). - -A transition from Suspend-to-Disk to the On state should take about 30 -seconds, though it's typically a bit more with the current -implementation. |